Parametric modulation magnetometer for crosstalk suppression in nuclear magnetic resonance gyroscopes

Nuclear magnetic resonance gyroscopes (NMRGs) detect the noble gas nuclear spin precession using an in situ parametric modulation Rb atomic magnetometer. However, conventional phase-sensitive demodulation (PSD) suffers from a degraded signal-to-noise ratio in detecting the nuclear spin precession signal due to interference from oscillating magnetic fields. This work demonstrates a single-axis phase-insensitive demodulation (PISD) magnetometer as a novel signal processing configuration for NMRGs. We detail the magnetometer construction and optimize its control parameters, achieving a sensitivity of 100 fT/${\mathrm{Hz}}^{1/2}$. Crucially, the PISD magnetometer significantly outperforms the traditional NMRG dual-axis PSD magnetometer in suppressing crosstalk from unwanted oscillating magnetic fields along orthogonal axes (x or y), reducing the crosstalk ratio of oscillating magnetic fields to 0.05%, nearly an order of magnitude improvement. To evaluate the effectiveness of this scheme in detecting nuclear spin precession signals under realistic interference conditions, the nuclear spin precession signals including crosstalk from the oscillating magnetic fields are measured under low pump-power conditions.